Volume III | Chapter 3 | Regional GeologyNext Back to catalogue index
by John R. Senior

This volume is concerned with that part of the Yorkshire Jurassic basin represented by the North Yorkshire Moors and Howardian Hills, and the chalk uplands of the Yorkshire Wolds, the fault-controlled Vale of Pickering, and the glacial lowlands of Holderness and the Vale of York. The geological structure of east Yorkshire and the underlying Mesozoic strata determine the topography of the area. This in turn must have been an important factor in the pattern of communications, and therefore the distribution of settlements, in this part of Yorkshire from Mesolithic times onwards.

The Middle to Upper Jurassic strata of the North Yorkshire Moors dip gently southwards towards the Vale of Pickering, giving the high sandstone capped Cleveland Hills to the north and the largely limestone Tabular Hills in the southern part of the Moors. Soft Kimmeridge Clays represent the highest strata of the Jurassic rocks in this area, and these underlie the Vale of Pickering, together with succeeding Lower Cretaceous Speeton Clays in the east of the vale. The extremely flat nature of the Vale of Pickering belies the structural complexity of the older Jurassic rocks below the Kimmeridge Clay/Speeton Clay cover. This is one segment of a deep and very complex grauben faulted area which stretches in an arcuate pattern from the Wash, off-shore of Lincolnshire and Flamborough Head, through the Vale of Pickering and the northern part of the Vale of York towards the Pennines, where it may be continued as the seismically active Craven Faults. Topographically this low-lying fault zone separates the dry uplands of the Chalk Wolds from the somewhat wetter uplands of the North Yorkshire Moors and the faults manifest themselves as abrupt truncations to limestone ridges, such as that found in the Ampleforth to Stonegrave area. During the advance of the Devensian ice sheet 25,000–18,000 years ago, the Vale of Pickering was the site of a large glacial lake, fed by summer melt-waters from the exposed North Yorkshire Moors and Yorkshire Wolds, and contained by the advancing North Sea ice sheet in the east and the ice sheet which occupied the Vale of York in the west. The waters of Lake Pickering escaped southwards via the spillway cut south of Malton and now occupied by the river Derwent. Varved lacustrine clays deposited by this late Quaternary lake only added to the general marshy nature of the Vale of Pickering, which made communications difficult.


A table listing the geological horizons of the stone types used for sculptures in the area covered by this volume be found on p. 00.

upper carboniferous sources

Millstone Grit Formation, Namurian

A stone commonly used for the York sculptures is of Millstone Grit type, a medium- to coarse-grained feldspathic rock, sometimes with pebble beds. This material was most certainly obtained by robbing the ashlar from the Roman fortress at Eboracum. The petrology and geochemistry of the sculpture stone can be matched with that of the East Carlton Grit (Marsdenian Stage, Namurian, Upper Carboniferous). The nearest possible source of this grit to York is in the vicinity of Hetchell Crag, near Thorner (SE 376 422; Fig. 5). There is a series of quarries in this area; some were opened for local eighteenth- and nineteenth-century building, but others, known locally as 'Pompocali', are perhaps Roman in origin. These quarries straddle the Roman road (Margary 1957, 134, no. 729), the southern branch of the road that linked Ilkley with Tadcaster and York, proceeding via Scarcroft, Thorner, and Bramham Park.

It is also possible that the Romans may have transported the East Carlton Grit from a source further from York, as the Roman road between Ilkley and York (Margary 1957, 133, no. 72b) passes to the south of East Carlton (SE 220431), the type area for this grit formation. Anglo-Scandinavian sculptures in Millstone Grit in the Yorkshire Wolds area at Kirby Grindalythe (nos. 2–3), Folkton (no. 2), and North Frodingham (no. 1), may have been exported there from York workshops.

Coal Measures sandstones, Westphalian

A small number of sculptures, including a coped grave-cover (York Minster 45), have been manufactured from a pale brown sandstone sedimentologically different from the Jurassic deltaic sandstones described below. The clue to the origin of this material may rest with an Anglian sculpture made of similar material and said to have originated at Weston Hall, Otley, now in the Yorkshire Museum (Bailey 1981a, 92). In the vicinity of Otley and Ilkley are thick sequences of Lower Coal Measure (Westphalian) sandstones, particularly the Elland Flags. Both towns are on a Roman road leading to York (Margary 1957, 133, no. 72b), and the road climbs the Otley-Chevin ridge, which could have been a possible source area for the Elland Flags sandstones.

upper permian source

Lower Magnesian Limestone

This building stone was also favoured by the Roman masons and many of the Anglo-Scandinavian sculptures in this material found inside and outside York may be reused Roman ashlar. Most of the sculptures are in a fine-grained, pale brown dolomitic limestone, characterized by often having small dolomite or calcite crystal-lined cavities, the sites of random gypsum crystals now dissolved away by post-depositional diagenetic processes. Occasionally the workshop used a diagenetically altered oolitic rock having a characteristic cellular texture resulting from the selective dissolving of the ooliths.

These dolomitic limestones were certainly used extensively in York by the Romans, for example, the Multangular Tower on the city defences (Kendal and Wroote 1924, 283) and in the principia under York Minster. They were most probably quarried in the vicinity of Tadcaster (Roman Calcaria) and possibly also in the area between Huddleston and New Micklefield, just to the east of the Roman road linking Doncaster with Tadcaster and York (Margary 1957, 146–8, nos. 28b–c). There has been a long tradition of using these Permian dolomites for building purposes and it is possible that the Anglo-Scandinavian masons and sculptors may have reworked the Old Roman quarries as the supply of readily available dressed stone at York gave out, thus forming a continuum with the Norman period, when large quantities of new dolomite rock were quarried.

Examples of sculptures in dolomitic limestone found at three localities outside York are probably yet more examples of exported artefacts from the York workshops. Indeed, two of them, the shafts found at Nunburnholme and Sutton upon Derwent, have roughly the same dimensions as the large dolomite ashlar blocks which are still to be found in the foundations of the principia at York. 5 (See also Chap. 10.)

jurassic sources

Outside York the majority of sculptures are made from Jurassic stone selected from a limited number of geological horizons for the qualities of durability, ease of working, and perhaps even the colour. Sometimes local availability was the overriding economic factor which is reflected in the poor quality and therefore the preservation of some of the sculptures. Most of the Lower Jurassic (the Lias) is unsuitable for sculpture and those limited thicknesses of suitable strata were not exploited during this period.

Saltwick Formation, Aalenian, Middle Jurassic

Middle Jurassic deltaic rocks are well exposed on the peripheral slopes of the North Yorkshire Moors, also on the top of the Cleveland Hills and on the sides of the deeply cut valleys of rivers such as the Seph, Dove, and Seven, which drain the North Yorkshire Moors. These deltaic sequences accumulated as river-deposited parallic deposits in the Jurassic basin and consist mainly of siltstones, shales, and thin, flaggy sandstones, cut by contemporary river channel systems. Redundant river channels became filled with clean, well sorted, cross-bedded sandstone bodies which provide the excellent architectural and artefact stone used from the Iron Age to the present day. Because these sandstones are usually found in discrete lenticular bodies, they rarely lend themselves to extensive modern exploitation, but were ideal materials for relatively small-scale Anglo-Scandinavian and medieval usage.

Individual channel bodies provide material of slightly differing qualities and the colour varies from white, through shades of yellow, pale brown, and brown, to reddish-brown, according to the increasing content of ferric hydroxides. It is at this stage in investigation very difficult to distinguish between stone obtained from different sources, but consideration of the rather fragmentary and tenuous evidence of communication patterns suggests locations for some of the material. The quarries at Aislaby, near Whitby (NZ 850087; Fig. 5) have had a long history of exploitation for good quality sandstone and were certainly known to (and, conceivably, owned by), the monastic community at Whitby. These extensive quarries provided white to pale yellowish sandstones at the base and a rich reddish-brown rock from the top; both types of material are well represented in the large collection of Anglo-Scandinavian sculptures at Lythe church, north-west of Whitby (NZ 851132; Fig. 5) (Collingwood 1911a, 287–98). Artefacts in similar materials have been found at many sites in the area of this volume (Fig. 1): notably Lastingham (nos. 1–10); and Hackness (nos. 2–4), which has documented connections with the Whitby community (see Chap. 2). Examples, including later pieces, are also found at Kirkdale (nos. 7–8), and even at Middleton and Sinnington, which were near to the southern end of Wade's Causeway, the Roman road which led directly from the quarry area at Aislaby near Whitby across the North Yorkshire Moors to meet the Vale of Pickering at a place also called Aislaby (SE 775857), thence traversing the clay vale to Amotherby, just west of Malton (SE 750733) (Margary 1957, 156–8, no. 81b). Sculptures in similar material have also been widely distributed through the rest of the area, with an exceptionally large collection being found at Sherburn, smaller numbers at Stonegrave and Hovingham, and important solitary examples occurring at Filey, Holme upon Spalding Moor, and Londesborough. It is tempting to theorize that much of the stone for these early sculptures may have been distributed from the quarry at Aislaby as a result of the influence of the Whitby community, but there is no doubt that there were other sources for comparable material which have not yet been recognized; for example, the raw material for the few sculptures found in the Helmsley area may have come from extensive sandstone bodies found on the valley sides of Bilsdale, the valley which lies to the north.

Ancaster Beds, Lincolnshire Limestone Formation, Lower Bajorcian, Middle Jurassic

Excavations of the principia beneath York Minster have revealed some Roman masonry worked in compact, shelly, oolitic limestone. There are two possible sources for this type of material, the Middle Jurassic Lincolnshire Limestone Formation from south of the Humber, and the Upper Jurassic Corallian Formation of the Malton district of Yorkshire. Petrological and textural evidence suggests the former area of origin. One sculpture from York has been manufactured from this material (see Minster 40).

Kellaways Rock Member, Callovian, Middle Jurassic

The crudely carved cross now in Hawnby Church is probably manufactured from fine-grained ferruginous marine Callovian sandstones of the Kellaways Rock Member and is most likely to be of local origin. Exposures of this sandstone are found in the valley of the river Rye between Hawnby and Rievaulx.

Lower Calcareous Grit Formation, Lower Oxfordian, Upper Jurassic

The earliest geologically competent rock type found in the Oxfordian stage in the Yorkshire basin is the Lower Calcareous Grit, a material having variable content of calcium carbonate cement and also of the remains, often silicified, of the algae Rhaxella. The greater the degree of silicification of the Rhaxella and the bigger the percentage of it forming the stone, the harder and less easily workable it is. Because of the variable hardness, this is not a good material for masonry or artefacts. It also very often contains body fossil fragments and the trace fossil, Thalassinoides (arthropod burrows), which disrupt the fabric of the rock. All the sculptures at Ellerburn seem to have been manufactured from fine- to medium-grained Lower Calcareous Grit of inferior quality found close by. Petrological examination of the strata exposed in small pits to the west of the church exactly matches that of the sculptures. The runic Anglian shaft in the church at Hackness (no. 1) is a notable example of the local use of Lower Calcareous Grit material with Thalassinoides bioturbation.

Middle Calcareous Grit Member, Coralline Oolite Formation, Middle Oxfordian, Upper Jurassic

It is possible that the Middle Calcareous Grit Member has furnished stone for sculptures found at some sites, particularly Sinnington, Middleton, Kirkbymoorside, Nunnington, and Stonegrave. So far, only one source for this medium-grained calcareous sandstone has been identified petrologically: one thin horizon in the old quarry area, immediately north east of Stonegrave church (SE 656779). This material was used for some of the sculptures inside the church (nos. 1 and 6), as well as for those at Nunnington and, perhaps, for one example at Wharram Percy (no. 1). Those sculptures on the north side of the Vale of Pickering may have been manufactured from Middle Calcareous Grit, which outcrops around Sinnington (SE 745857).

Coral Rag and Hildenley Limestone Members, Coralline Oolite Formation, Middle Oxfordian, Upper Jurassic

Only limited use has been made of the Coral Rag for sculpture manufacture, although this horizon has widespread distribution around the western part of the Vale of Pickering. The reason for this is that the coarse, shelly, and oolitic nature of the rock commonly results in frost damage; therefore the use of this material at Amotherby, Wharram Percy (nos. 2–4), and Kirby Grindalythe (no. 4), suggests local usage only. The Coral Rag outcrops in Amotherby, and the material used at the other localities very probably came from North Grimston (SE 846674), the nearest source of stone to these localities which would be in any way suitable for sculpture manufacture.

Both the fine-grained and coarsely fossiliferous varieties of Hildenley Limestone were extensively exploited by the Romans for use in Malton (Roman Derventio) and Eboracum (Senior forthcoming). The limited incidence of use of this material in Anglo-Scandinavian artefacts in this area suggests that reused Roman ashlar may have been utilized by the workshops. The only exception is the Anglian stele (no. 12) found in the excavations in York Minster, which may have been newly quarried material. The same may apply to the two grave-covers from the Minster in this material (nos. 41, 44).


Ancient pre-Roman lines of communication, such as the Regalis Via, Magna Via, and Rudland Rigg, avoided the marshy clay lowlands keeping to the drier ridgeways and upland areas, which also have ample evidence of habitation from the Mesolithic to Iron Age periods (Elgee and Elgee 1933; McDonnell 1963). When the area was Romanized, military routes also utilized the dry upland areas where possible, but the military surveyors were not averse to crossing marshy lowlands where necessary (e.g. Wade's Causeway, north of Amotherby (Margary 1957, no. 81b)).

The Anglian and later Scandinavian settlers inherited the pre-existing patterns of communications and the settlements can often be seen to reflect the known or inferred routes. For example, the important Anglian settlements of Stonegrave and Hovingham, both on spring-line sites on the margins of dry fault-controlled limestone blocks, are separated by the Coxwold-Gilling Gap, a marshy Kimmeridge Clay vale, which has only been drained from the thirteenth century onwards. Yet both settlements are on a branch of the Regalis Via, which crossed the marshland on a natural gravel bank deposited by meltwater rivers which flowed into this, the western part of the Devensian Lake Pickering.

The existing lines of communication, and the availability of suitable stone along these ways or in the vicinity of Anglo-Scandinavian sites, seem to be part of the raison d'etre behind the use of some types of stone for artefacts. Certainly stones whose carving dates from both the Anglian and Anglo-Scandinavian periods must have reached their present sites via these routes, arriving either as finished monuments or as rough blocks. Many of the route-ways were probably only passable to heavy wheeled transport during the summer time, and the size (and therefore weight) of the sculptures transported would be the limiting factor. At Hackness, for example, many of the smaller sculptures are made from Middle Jurassic sandstone from a source most probably in the Whitby area, whereas the large shaft (no. 1) is made of Lower Calcareous Grit (Upper Jurassic), available locally.

In York, ready-dressed stone was available. The Anglo-Scandinavian builders and sculptors of the city systematically robbed the ashlar from the Roman Fortress, there being no suitable stone to quarry in the immediate vicinity of the settlement. Sculptures made from this reused ashlar were exported to sites in the Yorkshire Wolds, where stone for sculpture manufacture is virtually non-existent. There is some material evidence that freshly quarried stone not traditionally used by the Romans in York was also imported, either as semi-worked or finished items. It is also possible that, as the supply of Roman ashlar failed, some of the Roman Magnesian Limestone quarries in the Tadcaster area were reopened.

I am grateful to D. Phillips for this information.

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